Added (mem)GeomUnion and (mem_)collect aggregates documentation, updated Centroid...

git-svn-id: http://svn.osgeo.org/postgis/trunk@356 b70326c6-7e19-0410-871a-916f4a2858ee

diff --git a/doc/postgis.xml b/doc/postgis.xml
index 71ed706a88857dd2a73441c09f48f6cdd9692f0e..705ef739f584d2729797d6f91eedf278f1de3712 100644 (file)
--- a/doc/postgis.xml
+++ b/doc/postgis.xml
@@ -1909,8 +1909,9 @@ intersection of this Geometry with anotherGeometry.
                                        <para>OGC SPEC s2.1.1.1</para>
                                </listitem> 
                                </varlistentry> 
+<!-- Should this be documented? -->
                                <varlistentry> 
-                               <term>geomunion(geometry,geometry)</term> 
+                               <term>GeomUnion(geometry,geometry)</term> 
                                <listitem> 
                                        <para> Returns a geometry that represents the point set union of
 this Geometry with anotherGeometry.
@@ -1922,6 +1923,24 @@ this Geometry with anotherGeometry.
                                </listitem> 
                                </varlistentry> 
                                <varlistentry> 
+                               <term>GeomUnion(geometry set)</term> 
+                               <listitem> 
+                                       <para> Returns a geometry that represents the point set union of
+this all Geometries in given set.
+                                       </para> 
+                                       <para>Performed by the GEOS module</para>
+                                       <para>Do not call with a GeometryCollection in the argument set</para>
+                                       <para>Not explicitly defined in OGC SPEC</para>
+                               </listitem> 
+                               </varlistentry> 
+                               <varlistentry> 
+                               <term>memGeomUnion(geometry set)</term> 
+                               <listitem> 
+                                       <para>Same as the above, only memory-friendly (uses less memory and more processor time). 
+                                       </para> 
+                               </listitem> 
+                               </varlistentry> 
+                               <varlistentry> 
                                <term>difference(geometry,geometry)</term> 
                                <listitem> 
                                        <para> Returns a geometry that represents the point set
@@ -2132,6 +2151,7 @@ is simple (does not pass through the same point more than once).
                                        <term>Centroid(geometry)</term>
                                        <listitem>
                                                <para>Returns the centroid of the geometry as a point.</para>
+                                               <para>Computation will be more accurate if performed by the GEOS module (enabled at compile time).</para>
                                        </listitem>
                                </varlistentry> 
                        </variablelist>
@@ -2460,7 +2480,7 @@ is simple (does not pass through the same point more than once).
                                        </listitem> 
                                </varlistentry> 
                                <varlistentry> 
-                                       <term>collect(geometry)</term> 
+                                       <term>collect(geometry set)</term> 
                                        <listitem> 
                                                <para>This function returns a GEOMETRYCOLLECTION object from a set
                                                  of geometries. The collect() function is an "aggregate" function in
@@ -2472,6 +2492,14 @@ is simple (does not pass through the same point more than once).
                                                </para> 
                                        </listitem> 
                                </varlistentry> 
+                               <varlistentry> 
+                                       <term>mem_collect(geometry set)</term> 
+                                       <listitem> 
+                                               <para>This does the the same of collect(geometry), only more
+                                               memory-friendly (uses less memory and more processor time).
+                                               </para> 
+                                       </listitem> 
+                               </varlistentry> 
                                <varlistentry> 
                                        <term>distance_spheroid(point, point, spheroid)</term> 
                                        <listitem> 
@@ -2483,7 +2511,7 @@ is simple (does not pass through the same point more than once).
                                        </listitem> 
                                </varlistentry> 
                                <varlistentry> 
-                                       <term>extent(geometry)</term> 
+                                       <term>extent(geometry set)</term> 
                                        <listitem> 
                                                <para>The extent() function is an "aggregate" function in the
                                                  terminology of PostgreSQL. That means that it operators on lists of data, in